The tool holders under consideration are the tubular-form parts of treatment instruments which the doctor holds as a gripping sleeve in the course of treatment. At its front a tool holder under consideration carries a treatment tool, e.g. a drill, and with its rear end it can be coupled by means of a plug-in/rotary coupling to a so-called supply part to which energy to power the treatment tool and also treatment media in associated fluid lines can be supplied through a supply cable. Both the drive energy line and the fluid lines pass through the plug-in/rotary coupling and continue in the tool holder. The fluid lines are usually air, water or spray lines which extend in the form of conduits or hoses as far as the front end of the tool holder and emerge there in order to be able to brought to bear at the treatment point, and/or as far as an air turbine arranged in the tool holder. An energy line can be an electrical line, a fluid line, particularly an air line, or also a mechanical connection, e.g. in the form of a spindle which transmits a torque. There are treatment instruments in which the drive motor is arranged in the supply part or the tool holder. For structural reasons the designs that have proved successful in practice are those in which an electric motor is arranged in the supply part and an air motor (in the case of a so-called turbine) in the tool holder. The drive connection between the drive motor and the treatment tool is made by means of mechanical couplings, gear trains and gear drives. A tool holder under consideration may be either a straight sleeve-like component or a so-called angled or elbow piece. In most cases, currently common plug-in/rotary couplings between the tool holder and the supply part are formed by a round plug-in stud arranged on the supply part and projecting therefrom and a plug-in hole arranged at the rear end of the tool holder and accommodating the plug-in stud. A tool holder of this kind therefore comprises mechanical, pneumatic and/or hydraulic functional elements.
When a tool holder is used to treat the human or animal body or to work on prostheses which are worn by patients, pollution and contamination by pathogens is unavoidable. It is thus necessary to clean and disinfect a tool holder after use. In view of the mechanical functional parts it is also necessary in this case to maintain the mechanics, e.g. with a special maintenance oil, in order to ensure uninterrupted operation and a long service life for the mechanical drive components.
A device which makes this possible is disclosed in U.S. Pat. No. 5,197,499; issued Mar. 30, 1993, which is assigned to the common assignee of this application. In this known arrangement, the cleaning, disinfecting and maintenance of at least one, preferably several tool holders takes place simultaneously, in a water bath in a container, a mounting in the container being associated with each tool holder, with which the associated tool holder can be mounted in an upright position. A compressed air line which terminates in the inside of the associated tool holder is associated with each mounting. The compressed air that can be supplied via the compressed air line can be optionally heated so that hot compressed air can be blown through the tool holder. An oil supply with an oil doser is also connected to the compressed air line via a line section so that oil can be optionally introduced into the cavity of the tool holder which accommodates the mechanical drive parts. In this known arrangement the cleaning and disinfecting of the tool holder externally and internally takes place by boiling in the water bath, with the possibility of adding cleaning agents and surfactants to the water bath. Internal cleaning and maintenance also takes place by means of hot compressed air and oil. For each tool holder treatment procedure the container provided is filled with hot water or heated. The liquor is pumped away after the treatment.